A coded optical beacon is currently being provided on automatic command to line of sight anti-tank guided missile systems, which provides a unique missile signature for automatic tracking and guidance. This signature should provide discrimination against normal background interference such as fires, horizon, glare, reflection, etc. and; discrimination against deliberate false targets such as flares, searchlights, and other optical jammers. These optical signatures provide a relatively low frequency signal output and are susceptible to false targets (optical jammers) having frequencies in this low frequency range.
One of the most probable sources for application as a high average intensity jammer at relatively low frequencies is the Xenon arc lamp. The frequency response of the Xenon arc lamp is a function of lamp size and current. Increasing the lamp size and increasing input power level reduces the frequency response of the optical output of the lamp. Since these lamps and other similar optical jammers are less efficient at higher frequencies, operation of an optical beacon at a relative high frequency (100 KHz or above) is desirable when the high frequency exceeds a maximum boundry of relative effectiveness of the jammers. In the past, high frequency operation of missile beacons has been prohibitive because of the physical characteristics of the radiating devices. Utilization of photodiode sources has overcome these limitations. Since pulse burst modulation (PBM) passes only frequencies within a high frequency passband, Xenon and other relative low frequency jammers offer little significant countermeasures threat to a high frequency coded system. For example, test results of a 75 watt Xenon arc lamp indicate that approximately 100 KHz can be construed to be a maximum boundary of relative effectiveness for Xenon jammers.